Home
Chapter Home
Jobs
Conferences
Fellowships
Books
Advertisement
Kidney tumor - cysts, children, adult benign
Reviewers: Christiane Rakozy, Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 29 January 2012, last major update January 2012
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.
Table of Contents for Kidney tumor - cysts, children, adult benign
Cystic non-neoplastic lesions: acquired cystic kidney disease, autosomal dominant polycystic kidney disease, autosomal recessive polycystic kidney disease, cystic renal dysplasia, glomerulocystic kidney, medullary sponge kidney, mesothelial cysts, nephronophthisis, simple cysts
Childhood neoplasms: anaplastic sarcoma, clear cell sarcoma, mesoblastic nephroma, metanephric stromal tumor, nephroblastomatosis / nephrogenic rests, neuroblastoma, oncocytoid carcinoma after neuroblastoma, ossifying tumor, renal cell carcinoma, rhabdoid tumor, translocation carcinoma (children), Wilms’ tumor of children
Benign (usually) adult tumors: classification, angiomyolipoma , cystic nephroma, epithelioid angiomyolipoma, fibroepithelial polyp of renal pelvis, glomus, hemangioma, inflammatory myofibroblastic tumor, juxtaglomerular, leiomyoma, lipoma, lymphangioma, medullary fibroma, metanephric adenofibroma, metanephric adenoma, mixed epithelial and stromal, myelolipoma, oncocytoma, oncocytosis, papillary adenoma, pelvic lipomatosis, perineurioma, post-kidney transplant, schwannoma, sinus histiocytosis, solitary fibrous tumor, spiradenocylindroma
Index (table of contents in alphabetical order)
A-E: acquired cystic kidney disease, anaplastic sarcoma, angiomyolipoma , autosomal dominant polycystic kidney disease, autosomal recessive polycystic kidney disease, classification, clear cell sarcoma (children), cystic nephroma, cystic renal dysplasia, epithelioid angiomyolipoma
F-L: fibroepithelial polyp of renal pelvis, glomerulocystic kidney, glomus, hemangioma, inflammatory myofibroblastic tumor, juxtaglomerular, leiomyoma, lipoma, lymphangioma, medullary fibroma, medullary sponge kidney, mesoblastic nephroma, mesothelial cysts, metanephric adenofibroma, metanephric adenoma, metanephric stromal tumor, mixed epithelial and stromal, myelolipoma, nephroblastomatosis / nephrogenic rests, nephronophthisis, neuroblastoma, oncocytoid carcinoma after neuroblastoma, oncocytoma, oncocytosis, ossifying tumor
P-Z: papillary adenoma, pelvic lipomatosis, perineurioma, post-kidney transplant tumors, renal cell carcinoma (children), rhabdoid tumor, schwannoma, simple cysts, sinus histiocytosis, solitary fibrous tumor, spiradenocylindroma, translocation carcinoma (children), Wilms’ tumor of children
Go to Kidney
nontumor
Go to Kidney
tumor - adult malignancies
top
AJCC Cancer Staging Manual (7th ed)
American Journal of Clinical Pathology
American Journal of Surgical Pathology
Archives of Pathology and Laboratory Medicine
Human Pathology
Modern Pathology
Murphy:
Tumors of the Kidney and Bladder (AFIP Atlas of Tumor Pathology, Series 3, Vol 11); 1994
Murphy: Tumors of the Kidney Bladder and Related Urinary Structures (AFIP Atlas of Tumor Pathology, 4th Series, Vol 1); 2004
Silva’s Diagnostic Renal Pathology 2009
Websites: PathoPic, Webpathology.com
Virtual slides: University of Iowa,
USCAP
Please refer to these primary references for more detailed discussions and photographs
Cystic non-neoplastic lesions
Simple cysts - Kidney-tumor chapter
Definition: not a disease, but an occasional finding that increases with age (0.1% in children, 20% at age 50+ years)
Clinical: 65% of renal masses, may be confused with cystic renal cell carcinoma, but avascular with smooth contours; may calcify; hemorrhage may cause acute pain
Treatment: percutaneous aspiration, continuous negative-pressure catheter drainage (AJR Am J Roentgenol 2008;190:1193), sclerotherapy
Gross: up to 10 cm, translucent with glistening membrane, filled with clear fluid, usually cortical
Gross images: simple cyst of upper pole; large cyst; multiple, smooth renal cysts filled with serous fluid; solitary, smooth kidney cyst (lower pole) filled with serous fluid; large cortical cysts with dark red blood
Micro: single layer of cuboidal, flattened or atrophic epithelium; may have thickened walls with hemosiderin-laden macrophages and atrophic epithelium
Kidney Neoplasms
Pediatric tumors
Anaplastic sarcoma - Kidney-tumor chapter
Definition: spindle cell tumor with anaplastic changes diffusely or in multiple foci, has bizarre pleomorphic cells and atypical mitotic figures; usually chondroid differentiation
First described in 2007 (Am J Surg Pathol 2007;31:1459)
Epidemiology: mean age 12 years, median 5 years, range 1-41 years, 60% female
Case reports: 24 year old woman (ScientificWorldJournal 2009;9:97)
Clinical: often presents at advanced stage; reasonably good outcome (10/13 alive at median 8 years follow up) although may die due to metastases to lung, liver and bones
Gross: mean 13 cm, up to 21 cm; usually has cystic component, 40% involve pelvi-calyceal system
Micro: fascicular pattern of spindle cells with anaplastic changes diffusely or in multiple foci, bizarre pleomorphic cells and atypical mitotic figures; usually chondroid differentiation (benign / malignant) due to islands of hyaline cartilage or chondroid matrix, occasional foci of osteoid and primitive blastema-like areas; no epithelial structures, no nephrogenic rests
Micro images: spindle cells in collagenous stroma, also anaplastic cells in cellular focus
Positive stains: vimentin, usually desmin, often p53
Negative stains: CAM 5.2, MyoD1, CD34, CD99, WT1
Molecular: no t(x;18) of synovial sarcoma, no ETV6-NTRK3 of mesoblastic nephroma
Differential diagnosis:
· anaplastic Wilms’ tumor - prominent blastema component, foci of epithelial differentiation, occasionally nephrogenic rests, no very atypical and wildly anaplastic cells in stroma and cartilage; blastema areas are WT1+ and CD56+
· sarcomatoid carcinoma - has keratin+ epithelial component
Clear cell sarcoma - Kidney-tumor chapter
Definition: monotonous proliferation of uniform small round cells with evenly distributed fine chromatin, separately by uniform vascular network
Also called bone metastasizing renal tumor
Epidemiology: mean age 36 months, range 2 months-14 years, peaks at ages 2-3 years; 2/3 male, graph
4% of childhood renal tumors; 20 new cases per year in US; rarely in teenagers / adults (Am J Surg Pathol 1999;23:1455)
Clinical: frequent relapse; bone and skull metastases common; also metastases to regional lymph nodes (29% at presentation), brain, lung, liver; metastases often 5 years or more after removal of primary tumor
Overall survival 69%, 98% for stage 1
Favorable prognostic factors: treatment with doxorubicin and low stage; death more common after combination chemotherapy other than doxorubicin
Case reports: congenital tumor with metastases (Virchows Arch 2005;446:566), 19 year old man with renal mass (UPMC #201)
Gross: large (mean 11 cm), well circumscribed, centered in central kidney or medulla; homogenous tan/gray or myxoid appearance; firm with occasional cysts
Gross images: large tan-yellow mass; well-circumscribed, bulging white tumor; fleshy yellow-tan tumor (fig 1A)
Micro: nests or cords of small cells with indistinct cell margins; light staining cytoplasm, round nuclei containing fine chromatin and grooves, no nucleoli, rare mitoses; only 20% have clear cells (due to vacuoles); vascularized stroma separating nests is alveolar and arborizing, scattered preexisting tubules or glomeruli are trapped in periphery of tumor; vascular invasion common; other patterns are myxoid (50%), sclerosing (35%, includes hyalinizing which has osteoid-like pattern resembling osteosarcoma), cellular (26%), epithelioid (13%, tumor cells align along vessels), palisading (11%), spindle (7%), storiform (4%) and anaplastic (3%)
Clear cell sarcoma (continued)
Micro images: classic pattern - tumor-kidney junction showing entrapment of individual nephrons by tumor cells extending into the adjacent renal parenchyma; evenly distributed vascular network; sheets of monotonous cells with indistinct cell margins, pale cytoplasm, round/oval nuclei with fine chromatin #1; #2; hypocellular spindle cell appearance; various images #1; #2; cell cords demarcated by delicate fibrovascular arcades #1; #2; numerous cytoplasmic vesicles; in this field, the tumor cytoplasm is more compact and less vesicular, and the nuclei are pale and frequently empty; cord cells are spindled, but vascular septa are still recognizable; proliferation of septal cells imparts a prominent spindled pattern; EGFR+
other findings - rosettes; pleomorphic tumor giant cells; hyalinizing pattern; epithelioid pattern; filigree pattern; myxoid and cystic pattern; palisading pattern reminiscent of schwannoma; pericytomatous pattern; sclerosing pattern; trabecular pattern
comparison with nephroblastoma - nephroblastoma (left) and clear cell sarcoma (right)-note the more uniform appearance and paler blue color of clear cell sarcoma; entrapped single renal tubules with cystic dilatation of one tubule, resembles nephroblastoma; cord cells have become condensed, creating cohesive epithelioid ribbons that can be confused with nephroblastoma
Cytology: moderate pale blue cytoplasm (Cytopathology 2008;19:80), cord cells with few stromal fragments; spindle cell variant has myxoid stromal fragments and septal cells, anaplastic variant has bizarre pleomorphic nuclei, coarse chromatin and atypical mitotic figures (Diagn Cytopathol 2005;33:83)
Cytology images: irregular nuclear borders, coarse chromatin and nuclear folding / grooves
Clear cell sarcoma (continued)
Positive stains: vimentin
Negative stains: keratin, EMA, S100, CD99, WT1, p53, desmin
EM: rare organelles, sparse cytoplasmic filaments, primitive cell junctions, complex cytoplasmic processes
Molecular: t(10;17)(q22;p13), t(10;17)(q11;p12), interstitial deletions of #14q (Arch Pathol Lab Med 2007;131:446)
Molecular images: t(10;17)(q22;p13) and interstitial deletion of 14q
DD: Wilms’ tumor - pushing border, more aggressively invasive, cells are less uniform and more hyperchromatic, epithelioid areas are keratin+
References: Am J Surg Pathol 2000;24:4, Hum Path 1985;16:1219, eMedicine
Benign (usually) adult tumors
Inflammatory myofibroblastic tumor - Kidney-tumor chapter
Also called inflammatory pseudotumor
Epidemiology: rare; median age 57 years, range 21-76 years; no gender preference; often asymptomatic
Case reports: 37 year old man and 54 year old woman (Arch Pathol Lab Med 2000;124:1209), 56 year old man (World J Surg Oncol 2007;5:106)
Treatment: nephrectomy; does not appear to recur (unless inadequate excision) or metastasize (Am J Surg Pathol 2003;27:658)
Gross: often involves renal pelvis and adjacent soft tissue or perirenal soft tissue; unencapsulated, partially circumscribed, 4-13 cm, composed of firm white tissue or myxoid/gelatinous; no hemorrhage, no necrosis
Gross images: polypoid lesion of renal pelvis and calyces
Micro: patterns are myxoid vascular (resembling nodular fasciitis or granulation tissue), compact spindle cell with aggregates of lymphocytes or plasma cells, or hypocellular fibrous with dense keloid-like fibrosis; composed of uniform, bland spindle cells and variable collagen, lymphocytes, plasma cells; occasionally has foam cells, osseous metaplasia or mild nuclear atypia; no/rare mitotic figures
Micro images: spindle cells and inflammatory cells in myxoid stroma; ill-defined spindle cell proliferation of renal pelvis; spindle cells in loose fascicular pattern; various images
stains - smooth muscle actin+; vimentin+, CD34
Positive stains: smooth muscle actin, HHF35, vimentin
Negative stains: ALK1, desmin, keratin, p53
Differential diagnosis:
· fibromatosis - culture-like fibroblasts, infiltrative border, usually no inflammatory infiltrate
· fibrous histiocytoma - storiform pattern of fibrohistiocytic cells, possibly giant cells
· spindle cell sarcoma - spindle cells exhibit atypia
Juxtaglomerular cell tumor - Kidney-tumor chapter
Rare, <100 cases described
Origin: specialized smooth muscle cells of the wall of the glomerular afferent arteriole (juxtaglomerular apparatus)
Epidemiology: mean age 23-38 years, also children
Associated with severe uncontrollable hypertension due to excess renin production; rarely secretes inactive renin with controllable or no hypertension
Other renin producing tumors (usually with only rare renin producing cells) are renal cell carcinoma, Wilms’ tumor, mesoblastic nephroma, hepatoblastoma, lung carcinoma, pancreatic adenocarcinoma, ovarian and soft tissue tumors, glioblastoma multiforme
Treatment: nephron-sparing surgery is curative; blood pressure may normalize after excision (J Hypertens 2008;26:368), benign behavior with no/rare recurrences or metastases (AJCP 2001;116:854)
Case reports: 10 year old boy with severe hypertension (Am J Surg Pathol 1994;18:837), 25 year old woman with high plasma renin activity (Arch Pathol Lab Med 1993;117:1161), 27 year old woman (Arch Pathol Lab Med 2004;128:e112), 46 year old man with 15 cm tumor that invaded renal vein and metastasized to both lungs (Am J Surg Pathol 2004;28:1098), 2 cases with a dominant papillary pattern (Hum Path 1993;24:1168)
Gross: well circumscribed, solid, gray-white-yellow, solitary, up to 8 cm; may have small foci of hemorrhage or small cystic spaces; usually doesn’t invade beyond kidney
Micro: sheets, nodules, papillary structures or trabeculae of variably sized tumor cells with granular eosinophilic cytoplasm; round, oval, and spindled nuclei with frequent atypia; edematous microcystic foci; papillary structures may have flat/cuboidal lining cells and inner polygonal cells; also hemorrhage, mast cells, prominent thick-walled or delicate blood vessels; hemangiopericytoma-like vascular pattern, hyalinized stroma; rarely coagulative tumor necrosis, minimal mitotic activity
Juxtaglomerular cell tumor (continued)
Micro images: sheets of cells with hemangiopericytoma-like vascular pattern #1; #2; organoid pattern; round or oval cells with abundant cytoplasm and vesicular nuclei and chronic inflammatory cells #1; #2; #3; epithelial cells with prominent granular cytoplasm; trabecular growth of uniform epithelioid cells in hemangiopericytoma-like vascular network; cells have granular cytoplasm and only mild pleomorphism; tumor (right) with adjacent clear cell carcinoma (left); various images
stains - renin granules are PAS+ diastase resistant
Positive stains: PAS, renin (strong and diffuse), renin RNA by ISH, vimentin, CD34 and CD117 (Arch Pathol Lab Med 2006;130:707); variable actin
Negative stains: HMB45, keratin, EMA
EM: rhomboid-shaped renin protogranules, secretory granules
EM images: rhomboid-shaped renin protogranules #1; #2
Cytogenetics: -9 and -11 (Hum Pathol 2008;39:459)
Differential diagnosis:
· metanephric adenoma - no papillary structures, no atypia, negative for PAS and renin
· papillary renal cell carcinoma - marked atypia, foam cells, negative for PAS and renin
Leiomyoma - Kidney-tumor chapter
Usually incidental, 1-3 mm in cortex, rarely in capsule (Acta Radiol 2006;47:752)
Micro images: 57 year old woman (Histol Histopathol 2007;22:883)
Gross images: firm circumscribed tumor with a whorled cut surface
Micro: benign spindle cell proliferation
Micro images: well circumscribed lesion #1; #2
Positive stains: alpha smooth muscle actin, h-caldesmon, calponin, muscle actin, myosin and desmin
Differential diagnosis: angiomyolipoma - usually vascular and lipomatous components; positive for melanocytic markers
Usually incidental, in cortex
Case reports: huge retroperitoneal mass (Br J Radiol 2006;79:e148)
Gross images: parapelvic lipomatosis; tumor appears to arise in hilar adipose tissue
Micro images: cortical tumor projects beneath the renal capsule
Differential diagnosis:
· angiomyolipoma - usually vascular and smooth muscle components; positive for melanocytic markers
· atypical lipomatous tumor of retroperitoneum - large tumor with hyperchromatic atypical nuclei
Lymphangioma - Kidney-tumor chapter
Also called renal lymphangiectasia
Epidemiology: mean age 34 years, 60% female (J Urol 1977;118:22)
Case reports: 28 year old man with microscopic hematuria (Radiology 2001;219:442), Hum Path 1992;23:465
Gross: well circumscribed, multicystic
Gross images: large cystic lesion adjacent to renal pelvis; large intrarenal lesion has honeycomb appearance
Micro images: cysts lined by flattened endothelium
Differential diagnosis: multilocular renal cyst
Medullary fibroma - Kidney-tumor chapter
Also called renomedullary interstitial cell tumor, renal hamartoma
Physiology: medullary interstitial cells regulate intrarenal blood flow, absorption of water and salt, and ultimately blood pressure through secretion of prostaglandins
Benign, usually found at autopsy (1 per 700 cases, Pol J Pathol 2008;59:21)
Gross: well circumscribed, gray-white firm nodule, < 1 cm, within pyramids
Gross images: multiple lesions in medullary pyramids #1; #2
Micro: fibroblast like cells, collagenous tissue and entrapped tubules at periphery
Micro images: fibroblast-like cells in myxoid or collagenous stroma #1; #2; circumscribed fibrogenic lesion among collecting tubules; small stellate cells, some with vacuolated cytoplasm; various images
Positive stains: Oil red O, Sudan black B
Negative stains: CD34
EM: resemble interstitial fibroblasts of kidney; large lipid droplets in cytoplasm
References: Hum Path 1972;3:559
Metanephric adenofibroma - Kidney-tumor chapter
Definition: biphasic, circumscribed tumor with focal embryonal epithelium identical to metanephric adenoma and bland spindled stroma
Formerly known as nephrogenic adenofibroma
Rare; < 50 cases reported
Member of metanephric tumor family, including metanephric adenoma (purely epithelial) and metanephric stromal tumor (purely stromal)
Can merge with the morphology of Wilms’ tumor, supporting the concept that these are related lesions (Am J Surg Pathol 2001;25:433)
Epidemiology: mean age 14 years, range 2-35 years; associated with papillary renal cell carcinoma, polycythemia, hypertension which resolves after nephrectomy (Am J Surg Pathol 1992;16:325)
Treatment: benign, excision is curative, chemotherapy not needed
Gross: solitary, nonencapsulated, vaguely circumscribed, irregular or spherical firm mass with tan-gray-white-yellow cut surface; variable cysts
Gross images: solid and vaguely nodular tumor
Micro: well circumscribed, biphasic tumor with focal embryonal epithelium identical to metanephric adenoma and bland spindle cell stroma; also intratumoral angiodysplasia, concentric cuffing of entrapped tubules ("onion skinning") and heterologous differentiation; spans morphologic spectrum between benign pure stromal and pure epithelial lesions; epithelial cells are bland with no mitotic figures; entrapped tubules may have papillary hyperplasia; numerous psammoma bodies
Micro images: spindle and myxoid stroma with adenomatous foci are characteristic; foci resembling collecting duct carcinoma are seen in some lesions
Positive stains: epithelium (stains like metanephric adenoma) - keratin; stroma - vimentin, fibronectin, CD34 (often)
Negative stains: epithelium - EMA; stroma - actin, desmin
Differential diagnosis:
· mesoblastic nephroma - congenital myofibroblastic tumor with collagen; irregular infiltrating edges
· Wilms’ tumor-epithelial predominant - triphasic tumor with undifferentiated blastema
Metanephric adenoma - Kidney-tumor chapter
Definition: pure epithelial tumor composed of embryonal-type epithelium with bland features
Rare, 0.2% of adult renal epithelial neoplasms; < 100 cases described
Also called metanephroid renal tumor, nephroblastoma-like adenoma of kidney, nephrogenic nephroma
First described in 1995 (Am J Surg Pathol 1995;19:1101)
Member of metanephric tumor family, including metanephric adenofibroma (mixed epithelial-stroma) and metanephric stromal tumor (purely stromal)
Epidemiology: mean 41 years but range is 5-83 years; 40-50% are incidental; 2/3 female; associated with polycythemia as a paraneoplastic syndrome in 12%
Typically benign
Origin: may arise from distal nephon/collecting duct; resembles developing metanephric tubular epithelium
May represent mature Wilms’ tumor as it resembles nephrogenic rests and maturing Wilms’ tumor histologically and immunohistochemically (Am J Surg Pathol 2001;25:1290), but 56% have changes at 2p13 not found in Wilms’ (Hum Path 2001;32:101)
Case reports: 7 year old girl with lung metastasis (Am J Surg Pathol 2000;24:570), 9 year old boy with multifocal tumor (Pathol Int 2009;59:49), 24 year old pregnant woman (Hum Pathol 2006;37:1227), 35 year old woman with passive seeding of hilar node (Arch Pathol Lab Med 2005;129:1317), 36 year old woman (Arch Pathol Lab Med 1999;123:1285), 44 year old woman (Arch Pathol Lab Med 2004;128:926), 54 year old woman (Mod Path 1996;9:329)
Gross: single, well circumscribed, non-encapsulated, tan-gray-white-yellow, solid/lobulated, mean 5 cm (range 0.3 to 15 cm); large tumors may have secondary cystic or hemorrhagic changes
Gross images: encapsulated tan tumor
Micro: small, uniform, closely packed tubules or papillae in loose stroma, composed of small cells with minimal cytoplasm, bland nuclei that may overlap, uniform chromatin, glomeruloid bodies, rare mitoses; may see hemorrhage, necrosis, calcifications (psammoma bodies), cysts; no atypia, no blastema, no/rare mitotic figures, no infiltrative growth, no vascular invasion
Metanephric adenoma (continued)
Micro images: well circumscribed tumor #1; #2; small tubules composed of bland cells with uniform nuclei #1; #2; solid appearance due to tight packing of acini/tubules #1; #2; glomeruloid bodies; papillary pattern; psammoma bodies; various images; nodal involvement; uniform closely packed tubules composed of small cells with minimal cytoplasm and oval nuclei, also psammoma bodies
case report - 36 year old woman - figure 1: large, tan, fleshy tumor; fig 2: nests and tubules of small blue cells
comparison with other tumors - metanephric adenoma, papillary renal cell carcinoma and Wilms’ tumor; compared to papillary carcinoma-solid variant and metastatic thyroid insular carcinoma #1; #2
stains - CD57+; WT1+; AMACR-; CK7-
Metanephric adenoma (continued)
Cytology: small, well differentiated epithelial tubules with bland nuclei, psammoma bodies (Cytopathology 2008;19:80, Acta Cytol 2007;51:468)
Positive stains: WT1 (strong/diffuse), CD57 (strong/diffuse), CK7 (focal), AE1 (focal), vimentin (solid areas)
Negative stains: AMACR (Mod Pathol 2006;19:218); also glycogen, CD56, desmin, NCAM, EMA
Molecular: no consistent abnormalities (Mod Path 2003;16:1060)
Molecular images: FISH shows 2 signals for #17 in most cells
EM: cilia on luminal side rest on abundant basement membrane
Differential diagnosis:
· metastatic insular thyroid carcinoma (Arch Pathol Lab Med 1999;123:415)
· papillary renal cell carcinoma (particularly solid variant) - red-brown with thick capsule, cells have more cytoplasm, nuclear grooves, prominent nucleoli; also foamy histiocytes, delicate vasculature; strong CK7, strong AE1, strong AMACR, EMA+, CD57-, WT1-, +7 and +17
· Wilms’ tumor - younger age, grossly tan-gray with hemorrhage or cysts, triphasic, WT1+, CD57-, vimentin-
Mixed epithelial and stromal tumor of kidney - Kidney-tumor chapter
Definition: benign tumor with cystic and solid growth of benign mesenchymal and epithelial elements in ovarian-type stroma
First described in 1998 (Pathol Res Pract 1998;194:445
Appears to be same disease but different morphology as cystic nephroma (Am J Surg Pathol 2009;33:72, Am J Surg Pathol 2007;31:489, Arch Pathol Lab Med 2006;130:80)
Also called cystic hamartoma of renal pelvis (Am J Surg Pathol 1993;17:1169) and adult mesoblastic nephroma (Am J Surg Pathol 1993;17:1029, Am J Surg Pathol 1998;22:827), although it lacks the genetic abnormalities of mesoblastic nephroma (Hum Path 2001;32:513)
Epidemiology: rare; almost exclusively perimenopausal women with obesity or receiving exogenous hormones, or men treated with lupron or DES (Am J Surg Pathol 2000;24:958).
Clinical: benign behavior
Case reports: 41 year old woman #1 (Arch Pathol Lab Med 1990;114:533), #2 in dialysis patient with bilateral tumors 5 years apart (Hum Pathol 2008;39:142), 53 year old woman with incidental cystic mass (Mod Path 1999;12:417), 58 year old man with no history of hormonal treatment (Urology 2008;71:168e7), 72 year old woman (Case of the Week #83), fat predominant tumor resembling angiomyolipoma (Int J Surg Pathol 2008;16:73), two cases with malignant transformation (Hum Pathol 2008;39:463), malignant tumor with rhabdoid differentiation (Hum Pathol 2007;38:1432)
Treatment: nephron-sparing surgery is recommended (Urology 2008;71:1142); does not recur or metastasize
Gross: in renal pelvis; well circumscribed but unencapsulated, mean 6 cm, range 3-12 cm, solid and cystic, yellow-tan
Gross images: multiloculated cystic tumor with smooth cyst lining; attached to renal pelvis by narrow pedicle
Micro: cystic and solid growth of benign mesenchymal and epithelial elements in ovarian-type stroma that contains smooth muscle, fibroblasts and myofibroblasts with embedded epithelial structures (tubules and cysts); cysts often have hobnailed epithelium; no blastema, no immature epithelial elements, no atypia
Classic: no hemorrhage, no necrosis, no/rare mitotic figures
Cellular: increased stromal cellularity, may have hemorrhage, necrosis, high mitotic index
Mixed epithelial and stromal tumor of kidney (continued)
Micro images: image #1; #2; #3; spindled myofibroblastic stromal component with tubular elements; various images #1; #2 (fig 1/2); stromal predominant tumor #1; #2; AE1/AE3; ER; PR
Virtual slides: #1
Positive stains: epithelium - keratin, EMA, CEA, vimentin, stroma - alpha smooth muscle actin, desmin, vimentin, ER, PR
Negative stains: HMB45, CD34; stromal cells - AE1-AE3, EMA, S100
EM: spindle cells have mitochondria, ribosomes and submembranous condensations composed of clusters of filaments; also basement membrane, abundant collagen fibers, dense plaques, pinocytotic vesicles, nearly continuous external lamina; rare endoplasmic reticulum
Differential diagnosis:
· clear cell renal cell carcinoma - more than occasional clear cells
· leiomyoma (particularly stromal predominant tumors, Arch Pathol Lab Med 2005;129:910) - no epithelial elements except trapped normal tissue, no ovarian-type stroma, not cystic
· nephroblastoma / cystic partially differentiated nephroblastoma - blastema present
· metanephric adenofibroma or adenoma - children/young adults, cysts uncommon, spindle cells are actin-, desmin-
· sarcomatoid renal cell carcinoma - atypia, renal cell carcinoma component present, necrosis, mitotic figures
· solitary fibrous tumor - no epithelial elements, no ovarian type stroma, usually not cystic
Myelolipoma of kidney - Kidney-tumor chapter
Usually in adrenal gland, < 50 cases elsewhere, <25 reported cases in kidney
Benign
Case reports: 65 year old man with hilar tumor (Arch Pathol Lab Med 2006;130:1049), 66 year old man with renal sinus tumor (Arch Pathol Lab Med 1999;123:631), 66 year old man with perirenal tumor (Arch Pathol Lab Med 1994;118:188)
Gross images: well delineated lesion (arrow) infiltrating into hilum
Micro: mixture of adipose tissue and normal hematopoietic cells; no bony spicules; not connected to medullary cavity of any bone by definition
Micro images: fat cells and hematopoietic cells; myelolipoma separated from renal parenchyma by fibrous band (arrow); various images
Oncocytoma - Kidney-tumor chapter
Definition: benign tumor of uniform round/polygonal cells with abundant, intensely eosinophilic and granular cytoplasm with uniform small, round, central nuclei with evenly dispersed chromatin
4-7% of adult renal epithelial tumors
Origin: intercalated cell of collecting duct
Epidemiology: adults age 50+; 2/3 men; usually incidental; may coexist with renal cell carcinoma; rarely associated with renal failure due to multiple tumors or large bilateral tumors (Arch Pathol Lab Med 2002;126:648)
Birt-Hogg-Dube’ syndrome: rare, autosomal dominant syndrome of small dome-shaped papular fibrofolliculomas of face, neck and upper trunk; associated with multiple renal tumors (mean 5.3), usually chromophobe carcinomas or oncocytomas, oncocytosis, pulmonary cysts and spontaneous pneumothorax (Am J Surg Pathol 2002;26:1542), associated with 17p12q11 abnormality involving folliculin protein (Arch Pathol Lab Med 2006;130:1865)
Xray images: CT shows circumscribed and homogeneous tumor except for an irregular central zone which proved to be a central scar; MR shows same tumor with prominent central scar
Case reports: 56 year old man with bilateral renal oncocytosis (Arch Pathol Lab Med 2004;128:e177), 62 year old man (Arch Pathol Lab Med 2003;127:1229), involving ectopic and crossed fused kidneys (Arch Pathol Lab Med 2002;126:648), with clear cell carcinoma (Am J Surg Pathol 1998;22:271), with focal chromophobe carcinoma and metastasis (Int J Surg Pathol 2009;17:158), encased within fibrotic shell resembling retroperitoneal fibrosis (Arch Pathol Lab Med 1994;118:1026); multilocular cystic tumor (J Clin Pathol 2006;59:223)
Treatment: benign behavior if follow strict diagnostic criteria, even if degenerative atypia (Am J Surg Pathol 1997;21:871); excision is curative
Gross: well circumscribed, no capsule, solid, homogenous, mahogany or brown-yellow (same as cortex), 3-6 cm, stellate central scar in larger lesions; 5% are bilateral or multifocal; may invade renal capsule or renal vein, 20% have gross hemorrhage but necrosis is rare; gross appearance is an important criteria
Gross images: mahogany brown tumor has stellate central scar #1; #2; #3; #4; #5; light brown tumor with central scar #1; #2; well circumscribed mahogany brown tumor #1; #2; #3; tumor has two stellate scarred zones; central cystic change
Oncocytoma (continued)
Micro: nesting, alveolar or tubular patterns (closely packed at periphery, more separated centrally) of uniform round/polygonal cells with abundant, intensely eosinophilic and granular cytoplasm, uniform small, round, central nuclei with evenly dispersed chromatin and smooth contour of nuclear membrane, occasional degenerative atypia (bizarre nuclear pleomorphism), focal vacuoles possible near areas of fibrosis; also “oncoblasts”-small cells with minimal cytoplasm and dense hyperchromatic nuclei; stroma is myxoid or hyalinized; occasionally cystic change, psammoma bodies, variably sized tubular structures, capsular / perinephric fat invasion (20%) or vascular invasion (5%); no papillary pattern (although may have small papillary fronds in areas of cystic change), no clear/spindle cells, no necrosis, no perinuclear halo; if mitotic figures in more than one 20x field, classify as eosinophilic chromophobe carcinoma
Note: grossly noted scar is composed of central loose stroma surrounded by closely packed nests of cells
Note: nuclear grading not needed since benign behavior (Am J Surg Pathol 1997;21:1)
Micro images: alveolar nests of cells with loose myxoid stroma #1; #2; #3; alveolar nests #1; #2; sheets of cells with abundant eosinophilic cytoplasm; cells have granular acidophilic cytoplasm and small, round, regular nuclei slightly less than 10 um; scarred zone has tumor cells separated by mature hyalinized fibrous connective tissue; incompletely differentiated oncocytes; various images
other patterns - cording; trabecular; tubulocystic #1; #2
other changes - focal degenerative atypia #1; #2; #3; osseous metaplasia; invasion of periphephric fat #1; #2; Birt-Hogg-Dubé associated tumors; multilocular cystic tumor
bilateral renal oncocytosis with renal failure - various images
Oncocytoma (continued)
stains - vimentin staining #1; #2; classic & eosinophilic variant of chromophobe carcinoma and oncocytoma, H&E and Hale’s colloidal iron; parvalbumin staining-G: positive (unusual); H: negative; EpCAM- (only focally positive) versus diffusely positive in chromophobe renal cell carcinoma
Cytology: large cells with homogenous granular cytoplasm, nuclei have no/mild nuclear membrane irregularities, tiny nucleoli, mild pleomorphism and only an occasional large, more hyperchromatic nucleus (Cancer 1999;87:161)
Cytology images: abundant granular cytoplasm and small, round and very regular nuclei #1; #2; small clusters and single cells with uniform cytoplasm; Diff-Quik shows homogeneous granular cytoplasm and round, regular nuclei without grooves
Positive stains: low molecular weight cytokeratin (CK 8/18, may be dot like), CK7 (may have intensely positive scattered cells in a background of negative staining cells), CK14 (strong), EMA, vimentin (focally positive in 73%, usually at edge of central scar or in small clusters scattered throughout the tumor, Arch Pathol Lab Med 2007;131:1782); also parvalbumin (calcium binding protein, Mod Path 2001;14:760), RON proto-oncogene (also in chromophobe renal cell carcinoma, Am J Surg Pathol 2004;28:1045), CD117/c-kit (Am J Surg Pathol 2004;28:676), E-cadherin, S100 (Hum Pathol 2006;37:462), kidney-specific cadherin (Am J Clin Pathol 2006;126:79)
Panels of markers to differentiate renal tumor subtypes:
(1) beta defensin1+, parvalbumin+, vimentin- in 100% (8/8) (small series, Am J Surg Pathol 2003;27:199)
(2) vimentin-(may be focally positive), GSTalpha-, EpCAM- (may be focally positive) (Arch Pathol Lab Med 2007;131:1290); second line markers are CD117+, CK7-
Negative stains: CK7 (may have focal positive cells), CK20 (variable), Sudan fat stain, Hale’s colloidal iron (may be positive at luminal surface in tubular areas), RCC-MA (Am J Surg Pathol 2001;25:1485), N-cadherin, CD10 (usually), low Ki-67 labeling index (Mod Path 1998;11:1115)
Oncocytoma (continued)
EM: marked increase in mitochondria, predominantly uniform and round with stacked parallel (lamellar) cristae, which causes the eosinophilia; few microvesicles in the apical portion of the cytoplasm, rare short and stubby microvilli; no/rare other organelles, lipid, glycogen, microvilli, brush border (Am J Surg Pathol 2000;24:1247)
EM images: cytoplasm is packed with large mitochondria #1; #2
Cytogenetics / molecular: chromosome 1 abnormalities in 88% of bilateral tumors versus 28% of single tumors (Arch Pathol Lab Med 2007;131:81, Am J Clin Pathol 2008;129:377); mt-DNA mutations are common (Hum Mol Genet 2008;17:986)
FISH images: loss of chromosome 1
Differential diagnosis:
· chromophobe carcinoma, eosinophilic variant - diffuse, solid growth but no nesting pattern; has distinct, thickened cell border; wrinkled nuclei with binucleation, perinuclear halos, mitotic figures, diffusely and strongly positive for Hale’s colloidal iron, microvesicles by EM
· clear cell carcinoma with granular cytoplasm - compact alveolar growth pattern; also hemorrhage, necrosis and frequent mitotic figures, long microvilli by EM, 3p-
References: eMedicine
Definition: diffuse renal involvement by numerous oncocytic lesions without necrosis, may be hemorrhagic
Rare; usually is at least 1 dominant nodule (2-10 cm), usually an oncocytoma, may be a chromophobe carcinoma or a hybrid
43% bilateral
Case reports: 45 year old woman with 11 tumors, all with normal appearing chromosomes (Mod Pathol 2008;21:498), 53 year old with > 100 tumors causing end stage renal disease (Arch Pathol Lab Med 2001;125:683)
Gross images: bilateral renal oncocytosis; kidney contained nine discrete tumors
Micro: multiple oncocytic nodules, often hybrid nodules with chromophobe carcinoma; oncocytes may infiltrate between benign glomeruli and tubules; often diffuse oncocytic change in nonneoplastic tubules, benign oncocytic cortical cysts
Micro images: small nodule; various images #1; #2
References: Am J Surg Pathol 1999;23:1094
Papillary adenoma - Kidney-tumor chapter
Commonly found at autopsy: 10% at age 21-40 years, 40% at age 70-90
Increasing numbers during life are being detected with more widespread whole body imaging
Associated with long term hemodialysis, acquired cystic disease (in 1/3)
Multiple adenomas associated with papillary renal cell carcinoma (Hum Pathol 2007;38:239)
Classification (WHO 2004):
Clearly benign: 0.5 cm or less, tubulopapillary architecture
Probably benign: same as “clearly benign” but up to 1 cm
Likely malignant: < 1 cm with solid growth pattern or clear cells
Malignant: 1 cm or more
References: Adv Urol 2008:974848
Case reports: 44 year old man with incidental lesion (Case of Week #43)
Gross: usually 5 mm or less, in cortex, encapsulated, yellow-gray
Gross images: small, well circumscribed cortical mass; 1.5 cm subcapsular tumor; adenoma is 8 cm, but has benign histology and is non-invasive
Micro: usually papillary; also tubular or tubulopapillary; cells have scant amphophilic to basophilic cytoplasm, round/oval nuclei with stippled to clumped chromatin and indistinct nucleoli; variable nuclear grooves, no/rare mitotic figures
Classified as type 1 (basophilic) or type 2 (eosinophilic), based on criteria for papillary renal cell carcinoma
Note: small tumors of clear cells are considered to be small renal cell carcinomas, clear cell type, with malignant potential
Micro images: circumscribed but nonencapsulated tumor; small cortical lesion; tiny tumor has papillary architecture; tubular structures lined by cuboidal cells with small nuclei; xanthoma cells in stroma; incidental tumor #1; #2; #3; type 1 (basophilic) tumors; figure A: type 1, fig B: type 2
Cytogenetics: gains of #7, 17, 16, 12 and 20 and loss of Y occur early in papillary renal cell neoplasia (Mod Path 2003;16:1053)
Cytogenetic images: figure A-single Y present in normal tubules; fig B-gain of #12 (3 signals) in papillary adenoma
Pelvic lipomatosis - Kidney-tumor chapter
Definition: overgrowth of normal fat in renal pelvis
Note: term also used for overgrowth of normal fat in perivesicle and perirectal spaces (i.e. true pelvis)
Associated with chronic pyelonephritis and renal lithiasis
Usually most prominent in renal hilum
Gross images: renal pelvic fat that clinically resembled malignancy
Differential diagnosis: lipoma
Perineurioma - Kidney-tumor chapter
Definition: benign tumor of perineurial cells; very rare in kidney
Case reports: 7 year old girl (Gen Diagn Pathol 1997;143:75), 26 year old man (Ann Pathol 2002;22:476), 66 year old woman (Arch Pathol Lab Med 1993;117:654)
Micro: storiform proliferation of delicate spindle cells with elongated processes; no long fascicles, no ectatic vessels
Micro images: site unknown (not kidney) - spindled tumor may resemble myxofibrosarcoma; delicate spindle cells with elongated processes; EMA+
Positive stains: EMA, type 4 collagen
Negative stains: S100
EM images: thin perineurial cell cytoplasmic processes with prominent pinocytotic vesicles
Differential diagnosis:
· low grade fibromyxoid sarcoma - focal to diffuse whirling, heavily collagenized stroma with abrupt transition to myxoid areas, often epithelioid areas, large collagen rosettes, infiltration of adjacent tissue
· schwannoma - long fascicles, ectatic blood vessels, S100+, EMA-, type 4 collagen-
Post-kidney transplant tumors - Kidney-tumor chapter
See also Lymphomas: non B cell chapter for discussion on post-transplant lymphoproliferative disorders
Tumors can be of donor origin (glioblastoma multiforme-Hum Path 1993;24:1256, lymphoma-Hum Path 1991;22:1291) or due to immunosuppression
Risk for cancers due to immunosuppression is 1.9; in Italian study, most common are viral related Kaposi’s sarcoma and EBV+ non-Hodgkin’s lymphoma, with common sites being native kidney, uterus and liver (Epidemiol Prev 2008;32:205); in Thailand study, most common are urothelial and hepatocellular carcinomas (Transplant Proc 2008;40:2403)
Also increased risk of skin cancers (Br J Dermatol 2006;154:498)
Hodgkin’s lymphoma: 2% of post-transplant lymphomas, mean 4 years after transplant; usually males; case report at Arch Pathol Lab Med 2001;125:1480; typical staining of Reed-Sternberg cells is CD15+, CD30+, EBER+, negative for B and T cell markers, micro images
Non-Hodgkin lymphoma: well recognized risk post-transplant, usually EBV associated extranodal B cell lymphomas that respond to reduction of immunosuppressive treatment; EBV promotes proliferation of B cells, which may escape T cell control
Post-transplant lymphoproliferative disorders: plasmacytic and polymorphic B cell hyperplasias are not monoclonal by flow cytometry; most B cell lymphomas or myelomas are clonal by flow cytometry, even if genotypic studies are negative (AJCP 2002;117:24); Reed-Sternberg-like cells are usually CD20+, EBV+, CD30+ but CD15- (Hum Path 1997;28:493)
Case reports of post kidney transplant tumors (not in kidney): bladder urothelial carcinoma, polyoma virus+ (Br J Cancer 2008;99:1383), Kaposi’s sarcoma in 5 year old boy (Hum Path 1992;23:956), plasmacytoma in tonsil (Arch Pathol Lab Med 2004;128:e76), T cell lymphoma (Am J Surg Pathol 1993;17:1046), T cell lymphoma of vulva (Am J Surg Pathol 1993;17:842)
Treatment: reduction in immunosuppression usually not sufficient for tumors in general, also need chemotherapy (Acta Haematol 2008;120:36)
Schwannoma - Kidney-tumor chapter
Definition: benign tumor of Schwann cells
Also called neurilemoma
Very rare, <20 cases reported in kidney through 2000
Epidemiology: mean age 47 years, range 18-84 years, usually asymptomatic (Mod Path 2000;13:851)
Treatment: resection is curative (Mod Pathol 2008;21:779)
Gross: renal pelvis or intrarenal; well demarcated, yellow-tan, smooth, bulging, mean 10 cm; compresses adjacent renal parenchyma
Gross images: yellow-tan lobulated intrarenal mass; multinodular masses of yellow-tan tissue with central cysts or softening
Micro: well circumscribed, often primarily cellular subtype (predominantly Antoni A pattern), may have myxoid and hypocellular areas (Antoni B); may have degenerative nuclear atypia (ancient schwannoma features), aggregates of foamy macrophages
Micro images: circumscribed and encapsulated, no infiltration; Antoni A areas with fascicular growth pattern, thick walled blood vessel and scattered lymphocytes; Antoni B area, hyalinized and dilated blood vessel; aggregates of foamy macrophages; various images and stains; strongly S100+
Positive stains: S100
Negative stains: cytokeratin, CD57/Leu7, smooth muscle actin, desmin, CD34
Differential diagnosis:
· angiomyolipoma - triphasic with blastema and epithelioid component
· sarcoma - spindle cells plus nuclear pleomorphism and nuclear atypia, infiltrative margins
· sarcomatoid carcinoma - marked atypia and renal cell carcinoma usually present, infiltrative margins, keratin+
Sinus histiocytosis with massive lymphadenopathy - Kidney-tumor chapter
Also called Rosai-Dorfman disease
Case reports: 13 year old boy #1 with large, asymptomatic renal mass with adjacent hilar adenopathy (Arch Pathol Lab Med 1985;109:867), #2 with 10 year clinical course of extensive involvement of multiple organ systems, leading to death (Arch Pathol Lab Med 1982;106:13), 31 year old man with generalized AA amyloidosis (Hum Path 2000;31:621), 37 year old with large bilateral masses of renal hilum (Arch Pathol Lab Med 1992;116:1366), 76 year old man with prostate carcinoma (Arch Pathol Lab Med 2006;130:1223)
Micro images: various images
Positive stains: S100
Negative stains: CD1a
Solitary fibrous tumor - Kidney-tumor chapter
Definition: benign (usually) tumor of patternless or storiform spindle cells with bland nuclear features, mixed with dense collagen
Rare in kidney, arises from serosal surfaces of pleura and other sites
Clinical: may be associated with hypoglycemia (Eur Urol 2008 Oct 1 [Epub ahead of print])
Case reports: 26 year old man (Can J Urol 2007;14:3583), 34 year old woman with malignant component (APMIS 2008;116:1020), 48 year old woman with capsular tumor (Am J Surg Pathol 1996;20:1288), 76 year old man with malignant tumor (Arch Pathol Lab Med 2006;130:857), 85 year old woman (Arch Pathol Lab Med 2006;130:117)
Treatment: excision; almost always benign behavior
Gross: often large (14 cm), well circumscribed
Micro: patternless or storiform pattern of bland spindle cells mixed with dense collagenous bands, may entrap renal tubules; often has hemangiopericytoma-like vascular pattern; variable lymphoplasmacytic infiltrate, variable myxoid change; usually no necrosis, no cystic change, no mitotic figures
Micro images: patternless pattern of bland spindle cells #1; #2; entrapped renal tubules; various images-malignant tumor; CD34+
case reports: 85 year old woman - fig 1: CT shows left renal mass, fig 2: well circumscribed lobulated mass arising from renal hilum, fig 3: variable cellular tumor with bland spindle cells, fig 4A: diffusely CD34+, 4B: bcl2+;
Positive stains: CD34, bcl2, CD99 (these three confirm the diagnosis); also vimentin, type IV collagen
Negative stains: cytokeratin, S100, muscle markers, melanocytic markers
EM: fibroblast-like cells (irregular nuclei, prominent Golgi, branching rough endoplasmic reticulum, variable mitochondria and intermediate filaments, no thin filaments with focal densities, no tonofilaments, no cell-cell junctions), no myoepithelial or epithelial differentiation
Solitary fibrous tumor (continued)
Differential diagnosis:
· cellular mesoblastic nephroma - congenital tumor of myofibroblasts with thin collagen fibers, smooth muscle actin+; has t(12;15)
· fibroepithelial polyp of renal pelvis - very rare, smooth glistening external surface, polyp covered by urothelium, collagen is present, but this is not a tumor of spindle cells
· fibroma - no dense collagen, usually not CD34+, bcl2+ or CD99+
· fibrosarcoma (on needle biopsies) - storiform pattern of atypical spindle cells
· gastrointestinal stromal tumor - kidney is a very unusual site, no dense collagenous bands, is CD117+
· inflammatory myofibroblastic tumor - tumor of myofibroblasts, actin+, desmin+, EBV+ by ISH, often keratin+, usually CD34-
· sarcomatoid renal cell carcinoma - infiltrative, atypical spindle cells, usually typical renal cell carcinoma component also present, keratin+ or vimentin+
· smooth muscle tumor - spindle cells have smooth muscle features, usually no dense collagen, positive for muscle markers
· synovial sarcoma - infiltrative, more atypical spindle cells, CD99+ but CD34-
References: Am J Surg Pathol 2001;25:1194
Spiradenocylindroma - Kidney-tumor chapter
Rare, single case report
Case reports: 58 year old man (Am J Surg Pathol 2002;26:119)
Gross: may arise in wall of renal cyst
Micro: large nodules exhibiting solid or trabecular architecture, conspicuous perivascular spaces or cylindromatous small tumor cell islands in jigsaw pattern; focal tubular structures and tumor cell rosettes with central PAS+ material; focal epidermoid differentiation
Positive stains: CK 5/6, 34betaE12, AE1/3, E-cadherin
Molecular: i(16p) affecting CYLD1 gene (involved in oncogenesis of familial cylindromatosis and some sporadic spiradenocylindromas)
End of Kidney tumor chapter - cysts, children, adult benign
Go to Kidney nontumor
Go to Kidney
tumor-adult malignancies
